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Drawing Triangles AAA
Resource ID#: 68423
Primary Type: Formative Assessment
This document was generated on CPALMS - www.cpalms.org
Students are asked to draw a triangle with given angle measures, and explain if these conditions
determine a unique triangle.
Subject(s): Mathematics
Grade Level(s): 7
Intended Audience: Educators
Freely Available: Yes
Keywords: MFAS, triangle, angles, sides
Instructional Component Type(s): Formative Assessment
Resource Collection: MFAS Formative Assessments
ATTACHMENTS
MFAS_DrawingTrianglesAAA_Worksheet.docx
MFAS_DrawingTrianglesAAA_Worksheet.pdf
FORMATIVE ASSESSMENT TASK
Instructions for Implementing the Task
This task can be implemented individually, with small groups, or with the whole class.
1. The teacher asks the student to complete the problems on the Drawing Triangles AAA
worksheet.
2. The teacher asks follow-up questions, as needed.
TASK RUBRIC
Getting Started
Misconception/Error
The student is unable to draw a triangle with the given conditions.
Examples of Student Work at this Level
The student draws a triangle with incorrect angle measures.
The student draws a figure that is not a triangle (e.g., an open figure with three sides).
Questions Eliciting Thinking
What are the features of a triangle?
What strategies would you use to draw a triangle given the measures of the angles? Where is a good place to beg
How would using a protractor help you draw a triangle with the given measurements?
Instructional Implications
Define a triangle as a polygon with three sides. Make clear that an open figure with three sides is not a triangle (
Provide the student with a manipulative such as
or software such as Geogebra (www.geogebra.org) to
Guide the student to draw a triangle with given conditions. Assist the student in using a protractor to draw and m
Next, ask the student to draw a working line and measure a length that is double the length of one side of the tria
intersect in the third vertex of the triangle. Have the student measure the lengths of these sides and compare them
as an opportunity to conclude:
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Three angle measures do not determine a unique triangle.
Two angle measures determine the measure of the third angle of the triangle.
Two angle measures and their included side length will determine a unique triangle.
Relate these conclusions to the relevant aspects of the exercise. Allow the student to further experiment to confir
Moving Forward
Misconception/Error
The student is unable to correctly determine if the given conditions form a unique triangle.
Examples of Student Work at this Level
The student is able to draw a triangle with angle measures 110°, 30°, and 40° but says it is not possible to draw m
The student justifies this decision by explaining:
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
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If you tried to draw a different triangle with the same angles, you’d get the same triangle but it would jus
There is only one way that you can make the angles the right measure.
No matter how you arrange the angles, they will always be the same distance from each side.
Questions Eliciting Thinking
How long are the sides of your triangle? Did they have to be these lengths?
What if you doubled the length of each side of the triangle? Would the angle measures change? How can you fin
Instructional Implications
Ask the student to draw a working line and measure a length that is double the length of one side of the triangle
in the third vertex of the triangle. Have the student measure the lengths of these sides and compare them to the le
opportunity to conclude:



Three angle measures do not determine a unique triangle.
Two angle measures determine the measure of the third angle of the triangle.
Two angle measures and their included side length will determine a unique triangle.
Relate these conclusions to the relevant aspects of the exercise. Allow the student to further experiment to confir
Almost There
Misconception/Error
The student does not adequately explain why the given conditions do not determine a unique triangle.
Examples of Student Work at this Level
The student is able to draw a triangle with angle measures 110°, 30°, and 40° and says it is possible to draw mor
The student explains:
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


You can extend the sides and not change the angles.
You can have the lengths different but the angles the same.
You could have the same angle measures but different lengths of the sides. For example, if you shortened
They would still have the same angle measures just different sides.
Questions Eliciting Thinking
Can you change the side to any length or do they have to be proportional to the original lengths? How do you kn
Show me (draw) an example of another triangle with different lengths but the same three angle measures. What
What vocabulary words describe this situation?
Do you know what proportional means?
Instructional Implications
Explain to the student that three angle measures do not determine a unique triangle. Provide opportunities for the
drawings, the lengths of sides change by a scale factor (e.g., proportionally) but the relationship between the side
explanation using mathematical terminology.
Got It
Misconception/Error
The student provides complete and correct responses to all components of the task.
Examples of Student Work at this Level
The student is able to draw a triangle with angle measures 110°, 30°, and 40° and says it is possible to draw mor
Questions Eliciting Thinking
What do you mean by increase or decrease all the lengths? Are you referring to addition and subtraction or mult
Instructional Implications
Address any issues with the use of notation or the placement of symbols in the drawing.
Pair the student with a Moving Forward partner to share strategies for drawing triangles.
Consider implementing the MFAS tasks Drawing Triangles SAS, Drawing Triangles ASA, Drawing Triangles S
ACCOMMODATIONS & RECOMMENDATIONS
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Special Materials Needed:
o
o
o
o
Drawing Triangles AAA worksheet
Ruler
Protractor
Technology such as Geogebra (optional)
SOURCE AND ACCESS INFORMATION
Contributed by: MFAS FCRSTEM
Name of Author/Source: MFAS FCRSTEM
District/Organization of Contributor(s): Okaloosa
Is this Resource freely Available? Yes
License: CPALMS License - no distribution - non commercial
Related Standards
Name
MAFS.7.G.1.2:
Description
Draw (freehand, with ruler and protractor, and with technology)
geometric shapes with given conditions. Focus on constructing
triangles from three measures of angles or sides, noticing when
the conditions determine a unique triangle, more than one
triangle, or no triangle.